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What is the Difference Between IPv6 vs IPv4

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Friday, January 2nd, 2015


IPv6 or IPv4? IP addresses are fundamental to networking and internet. Whenever you connect to the internet (or a local intranet), your computer or mobile device gets an IP address from the ISP or the organization (workplace, university etc.) to whose network you are connected. Without IP addresses, there would be no way to send or receive data over networks since the packets transmitted contain IP addresses of both the receiver (the computer or mobile device that makes the request) as well as the sender (usually a web server).

IPv4 is the fourth iteration of the Internet protocol that powers today’s internet and corporate intranets. IPv4 was developed in 1981 and it soon became the de facto networking protocol due to its features. However, the number of unique IP addresses available through IPv4 are extremely limited (by today’s standards) and this is certainly a pressing issue since we are about to run out of available IPv4 addresses. To address this and other security issues, an upgrade to the protocol, IPv6, was released in 1999.

Since IPv6 is the future of networking, it is important to understand the major differences between these two protocols:

1) Representation – IPv4 addresses are represented by a series of decimal numbers separated by a period (89.65.78.110) whereas IPv6 addresses are written as a series of hexadecimal numbers separated by a colon (3FFA:1234:AB5F:6GF6:23AB:68BC:90FG:56CD).

2) Number of available IPs – An IPv4 address is a 32 bit binary number so it can offer only 2^32 (4,294,967,296) IP addresses. On the other hand, IPv6 IPs are 128 bit binary numbers so there are 2^128 (340,282,366,920,938,463,463,374,607,431,768,211,456) unique IP addresses available. Due to extremely large number of available IPs, IPv6 is expected to cater to most networking needs for the foreseeable future.

3) IP Headers – All IP packets include a header but the information contained within an IPv4 and IPv6 header is significantly different. While IPv4 headers are 20 bytes long, IPv6 headers are double in size (40 bytes) which allows them to carry a lot more information. In addition, an IPv6 header is considered more efficient since legacy fields like Header Checksum, DF flag, Options and Internet Header Length are not longer supported plus new fields have been added to improve Quality of Service (QoS).

4) IP Address Configuration – IPv4 needs manual or DHCP (Dynamic Host Configuration protocol) configuration where IPv6 supports Stateless Address Auto Configuration (SLAAC) via DHCPv6 or ICMPv6 (Internet Control Message Protocol).

5) Address Resolution – IPv4 uses ARP (Address Resolution Protocol) to map IP addresses to Mac addresses whereas IPv6 relies on NDAR (Neighbor Discovery Address Resolution) for the job. Since ARP is present in the Link Layer, it is vulnerable to security attacks. NDAR addresses the security issues by residing in the Internet Layer which is far more secure and can be protected via IPSec (Internet Protocol Security) or other methods. IPv6 also includes built-in support for IPSec but IPv4 only supports it sparsely.

6) Transmission Modes – IPv4 includes support for unicast (one to one), multicast (one to many) and broadcast (one to all) modes while IPv6 supports unicast, multicast and anycast (one to closest) transmission modes.

7) Connectivity – IPv6 offers better connectivity options and is far easier to deploy since there is no NAT (Network Address Translation) traversal involved. NAT was needed in IPv4 since there were limited number of IPs available but it has been made redundant in IPv6.


January 2, 2015
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